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Abstract Mg₄(TiZnSn)₃, a rare-earth-free Mg-based multi-principal element alloy, was synthesized via high-energy ball milling and cold compaction. Potentiodynamic polarization in 0.1 M NaCl revealed spontaneous passivation with a corrosion current density of 8.96 ± 0.83 µA/cm²and a nobler than Mg corrosion potential of -1058.35 ± 15.91 mV_SCE. X-ray photoelectron spectroscopy confirmed the formation of a mixed oxide film containing ZnO, SnO₂, and TiO₂, contributing to the observed passivity. The alloy also exhibited improved mechanical performance, with a hardness of 5.06 ± 0.41 GPa and Young’s modulus of 109.24 ± 10 GPa. These results demonstrate that tailored multi-element alloying and powder metallurgy can synergistically enhance both corrosion resistance and mechanical properties in Mg alloys. 

ABSTRACT Environmental conditions such as temperature and resource availability can shape disease transmission by altering contact rates and/or the probability of infection given contact. However, interactive effects of these factors on transmission processes remain poorly understood. We develop mechanistic models and fit them to experimental data to uncover how temperature and resources jointly affect transmission of fungal parasites (Metschnikowia bicuspidata) in zooplankton hosts (Daphnia dentifera). Model competition revealed interactive effects of temperature and resources on both contact rates (host foraging) and the probability of infection given contact (per‐parasite susceptibility). Foraging rates increased with temperature and decreased with resources (via type‐II functional response), but this resource effect weakened at warmer temperatures due to shorter handling times. Per‐parasite susceptibility increased with resources at cooler temperatures but remained consistently high when warmer. Our analysis demonstrates that temperature and resources interact to shape transmission processes and provides a general theoretical framework for other host–parasite systems. 

Abstract A data set of 23,351 globular clusters (GCs) and ultracompact dwarfs (UCDs) in the Coma cluster of galaxies was built using Hubble Space Telescope Advanced Camera for Surveys data. Based on the standard magnitude cut ofM_V≤ −11, a total of 523 UCD candidates are found within this data set of compact stellar systems (CSS). From a color–magnitude diagram analysis built using this catalog, we find a clear mass–magnitude relation extending marginally into the UCD parameter space. The luminosity function defined by this data set shows an excess of sources at bright magnitudes, suggesting a bimodal formation scenario for UCDs. We estimate the number of UCDs with a different origin than GC to beN_UCD≳ 32 ± 1. We derive the total number of CSS within the core (1 Mpc) of Coma to beN_CSS≈ 69,400 ± 1400. The radial distribution of UCDs in Coma shows that, like GCs, UCDs agglomerate around three giant ellipticals: NGC 4874, NGC 4889, and IC 4051. We find UCDs are more centrally concentrated around these three ellipticals than GCs. IC 4051 has a satellite population of UCDs similar to NGC 4874 and NGC 4889. We estimate only ∼14% of UCDs inhabit the intracluster space (ICUCD) between galaxies in the region, in comparison to ∼24% for GCs (ICGC). We find red (metal-rich) UCDs are more likely located closer to a host galaxy, with blue (metal-poor) UCDs showing a greater dispersion and lower average density in the region. 

This study demonstrates the simultaneous achievement of high strength and excellent corrosion resistance in a Ni-free, high N austenitic stainless steel fabricated by laser powder bed fusion (PBF-LB). The formation of a single-phase austenitic structure was confirmed through X-ray diffraction analysis, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cyclic potentiodynamic polarization tests conducted in 0.6 M NaCl solution at room temperature revealed high breakdown potential (1187 ± 31 mVSCE), indicating excellent corrosion resistance for the additively manufactured Ni-free austenitic stainless steel compared to wrought 316L stainless steel. These findings were further supported by immersion tests in FeCl3 solution. The additively fabricated alloy’s yield strength and ultimate tensile strength exceeded 800 MPa and 1 GPa, respectively. The results highlight the potential for developing highly corrosion-resistant, high-strength Ni-free austenitic stainless steel by PBF-LB for possible applications for biomedical implants and structures relating to nuclear energy. 

Synopsis Dilution effects arise when increases in species diversity reduce disease risk, and amplification effects arise when the opposite occurs. Despite ample evidence for both phenomena, the mechanisms driving dilution and amplification effects and how they are mediated by environmental factors remain poorly understood. Mechanisms involving demographic rates or stage structure of hosts are particularly lacking in the diversity–disease literature. In Midwestern lakes, Metschnikowia bicuspidata parasites infect Daphnia dentifera focal hosts in autumn, with epidemics beginning when water is warm (∼25°C) and peaking when lakes have cooled (∼15°C). Epidemics are smaller in lakes with more Ceriodaphnia dubia alternative hosts, which serve as key diluters of disease. However, it is unclear whether seasonal changes in temperature affect their ability to alter host population dynamics and reduce disease. We conducted a mesocosm experiment to test how temperature (15, 20, or 25°C) mediated the effects of these key alternative hosts on density, stage structure, and disease dynamics in focal host populations. The experiment yielded several surprising results. First, focal hosts rapidly outcompeted alternative hosts at all temperatures. By the time parasites were added, alternative hosts had been almost completely excluded. Second, despite diluting disease in the field, initial presence of these alternative hosts amplified infection prevalence in the experiment. Third, this amplification arose as a legacy effect, lasting generations after alternative hosts were gone. Our explanation for this legacy amplification effect centers on focal host stage structure and demography. Competition with alternative hosts resulted in focal host populations that were more adult-biased when parasites were added, at all 3 temperatures. Additionally, host densities in these treatments increased more rapidly in the subsequent 10 days, consistent with reduced background death rates. Since adults consume more parasites than juveniles, and since exposed hosts must survive 10 days before producing infectious spores, these initial differences in stage structure and population growth seem to have set disease dynamics along amplified trajectories. These results highlight the need for a broader understanding of the mechanisms that can amplify or dilute disease, including altered host stage structure and mortality of exposed hosts in diverse communities. 

To address the challenges of sampling endangered or extinct species in the field, many studies have turned to historically underutilized sources of genetic material: natural history museums. Despite the fact that DNA from specimens collected decades or even hundreds of years ago is often fragmented and degraded, research has shown that historical DNA can still be used effectively to infer phylogenetic relationships and intra-specific patterns of population genetic structure. This synthesis aims to provide students and conservation practitioners with a solid understanding of the methodological strategies needed to apply genetic tools to natural history museum specimens. Specifically, we offer clear definitions and essential considerations for designing a conservation genomics project that includes both modern and historical samples. We recommend that instructors use this synthesis to introduce the foundational knowledge required for two companion exercises: “The Application of Conservation Museomics Approaches to the Protection of the Iberian Lynx (Lynx pardinus)” and “Designing a Conservation Genetics Project Incorporating DNA from Museum Specimens.” 

Abstract A common setting in astronomy is the availability of a small number of high-quality observations, and larger amounts of either lower-quality observations or synthetic data from simplified models. Time-domain astrophysics is a canonical example of this imbalance, with the number of supernovae observed photometrically outpacing the number observed spectroscopically by multiple orders of magnitude. At the same time, no data-driven models exist to understand these photometric and spectroscopic observables in a common context. Contrastive learning objectives, which have grown in popularity for aligning distinct data modalities in a shared embedding space, provide a potential solution to extract information from these modalities. We present Maven, the first foundation model for supernova science. To construct Maven, we first pre-train our model to align photometry and spectroscopy from 0.5 M synthetic supernovae using a contrastive objective. We then fine-tune the model on 4702 observed supernovae from the Zwicky transient facility. Maven reaches state-of-the-art performance on both classification and redshift estimation, despite the embeddings not being explicitly optimized for these tasks. Through ablation studies, we show that pre-training with synthetic data improves overall performance. In the upcoming era of the Vera C. Rubin observatory, Maven will serve as a valuable tool for leveraging large, unlabeled and multimodal time-domain datasets.